JPH0774060B2 - Medium transport device - Google Patents

Description

Detailed Description of the Invention

 [Table of Contents] Overview Industrial field of application Conventional technology Problems to be solved by the invention Means for solving problems (Fig. 1) Action Example (a) Description of one example (Fig. 2, (FIG. 3) (b) Description of essential parts of one embodiment (FIGS. 4 and 5) (c) Description of another embodiment

【The invention's effect】

[Outline] In a medium transport device that suctions and transports a medium by air,
An electromagnetic valve is provided between the vacuum pump for sucking air and the suction hole, a pressure sensor is provided between the electromagnetic valve and the vacuum pump, and a monitoring circuit for monitoring the suction state by the output of the pressure sensor is provided. The one that detects uplift due to poor adsorption of the medium. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a medium conveyance device that conveys a medium such as paper while suctioning the medium, and more particularly to a medium conveyance device that can monitor the suction state of the medium. 2. Description of the Related Art A medium transport device for transporting a medium is used in a wide variety of fields. For example, in a recording device, a medium is transported and recorded on the medium. Has been. [Prior Art] In such a medium carrying device, in order to carry out highly accurate carrying, in a system of carrying by contact with a carrying means such as a roller or a belt, the carrying accuracy is influenced by an adhesive force. For this reason, there is used a device in which a suction hole is provided in the transporting means and the medium is positively sucked and transported by the transporting means. In such a transporting apparatus using suction, it is necessary to monitor the transporting state of the medium, and therefore, the transporting state has been monitored by an optical sensor or the like. [Problems to be Solved by the Invention] In such a conveyance device using air suction, it is possible to detect a jam by using the above-mentioned optical sensor or the like, but it is not possible to detect the floating of the medium from the suction surface. There is a problem. For example, in an electrophotographic recording apparatus such as a laser printer, when a medium (photosensitive paper) is lifted up due to a suction failure, a charging failure occurs or the focus position of writing light of a laser writing system is different, and thus a normal writing is performed. Recording becomes impossible. It is an object of the present invention to provide a medium carrying device capable of monitoring the sucked state of a medium when carrying by air suction. [Means for Solving Problems] FIG. 1 is a diagram illustrating the principle of the present invention. In the figure, 10 is a feed drum as a conveying means that rotates in the direction of the arrow, and 10a is a suction hole that is provided on the circumference of the feed drum 10 to adsorb the medium CP and to rotate the feed drum 10. 16 is a solenoid valve that conveys the medium CP,
A device that is provided between a vacuum pump and a suction hole 10a, which will be described later, and connects / disconnects between the vacuum pump and the suction hole 10a.
Is a vacuum pump for sucking the suction holes 10a under vacuum, 1
Reference numeral 8 is a pressure sensor, which detects the vacuum pressure by the vacuum pump 17, and 19 is a monitoring circuit, which monitors the suction state of the medium CP by the suction holes 10a based on the output of the pressure sensor 18. [Operation] In the present invention, in a good suction state, the air pressure due to suction is equal to or higher than a certain specified value. Therefore, this air pressure is detected by the pressure sensor 18, and the suction hole 10a of the medium CP is detected.
The adsorption state is monitored by. In addition, the solenoid valve 16 connects to the suction hole 10a and the vacuum pump 17 when necessary for conveyance, and the monitoring circuit 19 uses the pressure sensor at that time.
The detection output of 18 is monitored so that the adsorption state can be accurately monitored. Embodiments (a) Description of One Embodiment FIG. 2 is an overall configuration diagram of one embodiment of the present invention, showing a plate making apparatus using an electrophotographic system as an example. In the figure, the same components as those shown in FIG. 1 are designated by the same symbols,
Reference numeral 1 denotes a recording / conveying unit, which adsorbs a medium (photosensitive paper) CP in the width direction of the feed drum 10 by the suction holes 10a and records while conveying the photosensitive paper CP by rotation of the feed drum 10. The photosensitive paper CP sent by 15a, 15b is adsorbed by the adsorption hole 10a, and is brought into close contact with the feed drum 10 by the pressing rollers 11a, 11b, 11c. After the charging, the laser writing unit 14 writes (exposes) a dot pattern, and the separation claw 12 separates the photosensitive paper CP from the feed drum 10. Reference numeral 2 denotes a paper feeding unit, which is a pair of roll-shaped photosensitive paper 20. Of the feed rollers 22a, 22b, 24a, 24b of the sheet feeding device, the cutter 23 cuts the sheet to a predetermined length, and the sheet is fed to the recording / conveying unit 1. The sensor detects presence / absence and width of the sheet CP.
21 is provided, and 3 is a developing and fixing unit, which is a developing device 30 for developing the photosensitive paper CP separated by the separation claws 12 by wet development, and a developing device 30 which sends the developing rollers 30a and 31b. It has a fixing device 32 which heats and fixes the used photosensitive paper CP and sends it out by the paper discharge rollers 33a and 33b. PS1 and PS2 are sensors that detect the arrival of the photosensitive paper CP. The operation of the configuration of the embodiment of FIG. 2 will be described with reference to FIG. The roll paper 20 is set in the paper feed unit 2, and the feed roller 22
When the leading ends of the sheets a and 22b are set, the sensor 21 detects the sheet width as described later. Upon start-up, the feed rollers 22a, 22b, 24a, 24b and the timing rows 15a, 15b rotate, and the photosensitive paper CP is fed. When the leading edge of the photosensitive paper CP passes through the timing rollers 15a and 15b and is detected by the sensor PS1, these rollers 22a and 2b
2b, 24a, 24b stop, the cutter 23 operates, and the paper is cut. Then, the front end of the photosensitive paper CP is adsorbed by the adsorption holes 10a provided on the surface of the feed drum 10 in the width direction. Next, the timing rollers 15a and 15b and the feed rollers 24a and 24b
And the feed drum 10 rotates simultaneously. Therefore, the photosensitive paper CP
From the state shown in FIG. 1, as shown in FIG. 3 (A), when the pressing rollers 11a, 11b, 11c are brought into close contact with the feed drum 10 and fed, and the sensor PS2 detects the leading end of the photosensitive paper CP, printing is performed. At the start, the charger 13 operates, the corona charging is performed on the photosensitive paper CP, and the photosensitive paper charged by the laser writing unit 14 is further started.
The CP is exposed, and a static belt image is formed on the photosensitive paper CP. Immediately after the front end of the photosensitive paper CP has passed the front end of the pressing roller 11a, the front end of the photosensitive paper CP is moved by the separating claw 12 as shown in FIG. 3 (B).
As shown in FIG. 3, the photosensitive paper separated from the feed drum 10 enters the developing device 30, is developed, is then fixed by the fixing device 32, and is discharged by the paper discharge rollers 33a and 33b. In this way, an image is formed on the photosensitive paper CP by an electrophotographic method, a plate is prepared, and the plate is provided to an offset printing machine. The photosensitive paper CP is conveyed in a form in which the leading end is closely attached to the feed drum 10 by the suction hole 10a and is also brought into close contact with the feed drum 10 by holding down the pressing force of the pressing rollers 11a to 11c. It is possible to perform extremely high density recording that can be evaluated as a plate. In this example, the entire circumference of the feed drum 10 is not used as the traveling path of the photosensitive paper, but a part is used as the traveling path. Partial lifting from the paper feed drum 10 is less likely to occur,
It is possible to realize conveyance that is in complete contact with the feed drum 10. (B) Description of Main Part of One Embodiment FIG. 4 is a main part configuration diagram of the embodiment shown in FIG. In the figure, the same parts as those shown in FIG. 1 and FIG. 2 are shown by the same symbols, and 100, 101 and 102 are suction parts respectively, and three kinds of suction holes 10a are formed in the surface width direction of the feed drum 10. Sheet widths (B4 version, B4 wide version, A3 version) are provided so that switching is possible, 16a, 16b, 16c are solenoid valves, respectively, and disconnection between the suction unit 100, 101, 102 and the vacuum pump 17
For connection, 21a is a paper end photo sensor (hereinafter referred to as PEPS), 21b and 21c are paper width photo sensors (hereinafter referred to as PSZL and PSZW), and the width of the set paper and the presence / absence of paper. 41a, 41b, 41c are drivers for opening and closing the corresponding solenoid valves 16a, 16b, 16c according to the instructions of the MPU, which will be described later, and 40 is a microprocessor. (Hereinafter referred to as MPU), which controls the operation of each part and also PE of the sensor 21.
PS21a, PSZL21b, PSZW21c outputs P1, P2, P3 to detect the presence or absence of paper and the width of the paper, specify the suction area, and the monitoring circuit 19 to check the suction pressure check enable signal.
The one that issues the VCS and the vacuum pressure check enable signal PCS, 19a is an inverter, and the detection output S of the pressure sensor 18
Inverting PS, and 19b and 19c are AND gates respectively, and detect output SPS and vacuum pressure check enable signal P respectively.
The logical product of CS and the suction pressure check enable signal VCS is calculated, and the vacuum pump abnormality signal PES and the suction abnormality signal VES are notified to the MPU 40. In this example, it is assumed that there are three types of paper to be handled, that is, B4 version, B4 wide version, and A3 version, and the conveyance is performed on the basis of the left end of the figure. Therefore, the three suction parts 100, 10 are arranged in the width direction of the feed drum 10.
Adsorption holes 10a composed of 1,102 are provided, and solenoid valves 16a to 16c are provided correspondingly. On the other hand, in order to detect the width of the set paper, the sensor 21
PEPS21a, PSZL21b, PSZW21c are provided, and the MPU 40 determines the paper width based on the outputs P1 to P3 of these sensors. That is, when the output P1 is "0", the paper does not cover the sensor 21 at all, and it is determined that there is no paper. When only the output P1 is "1", only the B4 version set and the outputs P1 and P2 are output. B in the "1" state
4 When the wide version set and outputs P1, P2, P3 are all "1", it is judged as the A3 version set. Accordingly, if the MPU 40 determines that the B4 version set, the suction area is set to the B4 version, only the driver 41a is driven, and the solenoid valve 1
Only 6a is opened and only the suction unit 100 is connected to the vacuum pump 17. Also, if it is judged that the B4 wide version set, the suction area
If the B4 wide version is used, only the drivers 41a and 41b are driven, only the solenoid valves 16a and 16b are opened, only the adsorption parts 100 and 101 are connected to the vacuum pump 17, and if the A3 version set is determined, the suction area is A3.
As a plate, drives the drivers 41a, 41b, 41c, and solenoid valves 16a to 16
Open c and connect the adsorption units 100 to 102 to the vacuum pump 17. Therefore, the suction area of the suction hole 10a of the feed drum 10 is set according to the width of the set sheet, and the vacuum pump 17 does not suck the portion without the sheet which is not necessary, so that the suction force is unbalanced. It does not occur, and the suction force of the suction area actually required for suction does not weaken. FIG. 5 is an explanatory view of the pressure check operation of FIG. The output SPS of the pressure sensor 18 is
High level, low level if below specified value. When all the solenoid valves 16a to 16c are closed, the vacuum pressure check enable signal PCS is high, and the AND gate 19b
Is open. Therefore, the output of the output SPS of the pressure sensor 18, which is inverted by the inverter 19a, is directly output as the vacuum pump abnormality signal PES. Therefore, when the vacuum pressure of the vacuum pump 17 is normal, the output of the output SPS of the pressure sensor 18 is at a high level and the vacuum pump abnormality signal PES remains at a low level, but as indicated by the dotted line of the arrow, When the output of the output SPS of the pressure sensor 18 is low level, that is, when the vacuum pressure of the vacuum pump 17 is abnormal, the vacuum pump abnormality signal PES becomes high level and the solenoid valve 16a ~
The normality of the vacuum pressure of the vacuum pump 17 is checked at the time of non-adsorption when the 16c is closed. On the other hand, as described above, when the sensor PS1 detects the leading edge of the sheet, the MPU 40 causes the solenoid valves 16a to 16c to be moved according to the sheet width of the sensor 21.
Is driven to open via the drivers 41a to 41c. As a result, the vacuum pressure check enable signal PCS becomes low level, and the AND gate 19b is closed. Since the paper suction state from the open driving of the electromagnetic valve 16a~16c becomes unstable as the output SPS between the pressure sensor 18 to stabilize, after a time t ₁ has elapsed during this period, MPU 40 is suction pressure Chie get enable signal VCS Is set to a high level, the AND gate 19c is opened, and the output of the pressure sensor 18 SPS inverter 19
The inverted output by a is output to the MPU 40 as the adsorption abnormality signal VES. When the adsorption pressure is normal, the adsorption abnormality signal VES remains at the low level, but when the output SPS of the pressure sensor 18 becomes the low level as indicated by the dotted line, that is, due to adsorption failure, solenoid valve operation failure, etc. If the adsorption pressure drops abnormally, the adsorption error signal VES becomes high level as shown by the dotted line.
Absorption abnormality is notified to MPU40. In this way, the suction pressure at the time of sucking the paper by the opening drive of the solenoid valves 16a to 16c is checked. Further, after the suction pressure Chie get enable signal VCS with closed solenoid valve 16a~16c to a low level, the vacuum pressure Chie get enable signal pressure at a time t ₂ to stabilize PCS
Is set to a high level to perform a pressure check during non-adsorption except for the transient period. In this way, the single pressure sensor 18 can monitor the adsorption pressure and the vacuum pressure during non-adsorption. (C) Description of Other Embodiments In the above-described embodiments, the feed drum is used as the feed means, but other known feed means such as a feed belt may be used, and the feed drum may be attached to a part of the feed drum. Although the holes are provided, they may be provided at many places. Further, although the example of using it in the plate making apparatus has been described, it can also be used in other apparatuses. Although the present invention has been described with reference to the embodiments, the present invention can be variously modified according to the gist of the present invention, and these modifications are not excluded from the present invention. [Effects of the Invention] As described above, according to the present invention, the following effects are achieved. An electromagnetic valve is provided between the suction hole and the vacuum pump, the electromagnetic valve is opened according to the medium detection output of the sensor, and the output of the pressure sensor is monitored. Therefore, the suction state of the medium by the suction hole can be monitored. Since the pressure sensor is provided between the solenoid valve and the vacuum pump and the output of the pressure sensor is monitored with the solenoid valve closed, the state of the vacuum pump can also be checked.

[Brief description of drawings]

 FIG. 1 is an explanatory view of the principle of the present invention, FIG. 2 is an overall configuration diagram of an embodiment of the present invention, FIG. 3 is an explanatory diagram of the feeding operation of the configuration of FIG. 2, and FIG. FIG. 5 is an explanatory diagram of a pressure check operation of the configuration of FIG. In the figure, 10 ... Feed drum (conveyor), 10a ... Adsorption hole, 16 ... Solenoid valve, 17 ... Vacuum pump, 18 ... Pressure sensor, 19 ... Monitoring circuit.

Claims (1)

[Claims] 1. A medium carrying device having a carrying means having a suction hole (10a) for sucking a medium by air and carrying the medium while sucking the medium in the suction hole (10a), wherein the suction hole (10a) and a vacuum are provided. A solenoid valve (16) provided between the pump (17), a pressure sensor (18) provided between the vacuum pump (17) and the solenoid valve (16), and a transfer position of the medium. Sensor (PS
1) and the solenoid valve (1) according to the medium detection output of the sensor (PS1).
6) is opened and the solenoid valve (16) is closed, the vacuum pressure of the vacuum pump (17) is monitored by the output of the pressure sensor (18), and the solenoid valve (16) is opened. In the state, a monitoring circuit (19, 40) for monitoring the suction state of the medium by the suction hole (10a) by the output of the pressure sensor (18) is provided.